Recent content by Asdrael

Hah well, that's a mistake you will do again ;) Fusion is fine really. Just a matter of slowly building your library the way you like by getting component from places like Mouser and/or making your own. Once you have this it's just schematic, then building slowly the PCB. You'll get hte hang of...

Bypassed fuse allows you to avoid putting a light to monitor switch on. At least once.

Lovely vintage builds! And ouch for the bias diode… a costly reminder to always follow a good startup procedure. Did a similar mistake once and luckily only blew up a pair of KT77. But yeah not again.

I recently put a NFB pot in my home made VH4 and it’s the best thing I have ever done on that amp. I think something similar should be on every home made amp really… a regular pot works, no need for anything fancy too. More versatile than a switch (wait you could probably do a push pull to get...

I understood it so that the cathode resistor change would be more of a voicing option, not to compensate the operating point from the rectifier voltage change, and I was thinking about the preamp. So your reasoning makes sense :) Not even sure how they do it on an actual rectifier...

An OT also has a frequency response. Generally speaking a HiFi OT will have a broad frequency response (especially up to much higher frequencies) than an instrument OT and that is definitely not always desirable.

Cool project, even cooler presentation ;) I'll gladly follow this one! One comment though, if I understood your DPDT idea: I would advise you to do this one as two separate switches. - One for the cathode resistor, and in parallel instead of series. Should have less pop, and then you can use...

Fair enough! Do you reckon it could fit in a "floor amp" type of case?

Interesting! The thermistor I wouldn't worry about the remaining resistance really. Frequent in those situations. The 317 heatsink is pretty small tho, I would have tried to fit a bigger one on... Also, when you say 220k/3k9 gives a "classical" 12ax7 response, is it with the same capacitor...

Doing a LED front panel from your 12V DC is straightforward. Depending on how the standby is wired you could even do a dual Color for standby/on. I went dual Color on my amp for the plexi front depending on the channel I am on. Three LEDs running at 50% of their max power is plenty enough really.

Congrats! Needs some LEDs tho 😁

Is the amp close to an EM source when you play? Computer, monitor etc? From your layout picture, I would say that probably plays a huge role as well. Seems you have your grid stoppers on the pins though so there is that already.

And make sure they area all DPDT on/on/on and a mix of type one and two just for fun.

From what I see from the schematics, there would be too many changes to do it with a single mechanical switch. You would have to build a series of relays to do the changes, and I think there would be some pretty nasty pop even with smart implementation. Probably smarter to try out both...

Could you diagnose where the hum came from before the changes btw? I would say a shielded input to v1 grid stopper is mandatory. Raising the grid stoppers probably did a lot for you there.